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Questions tagged [experimental-technique]

filling in the unspecified details of elegant-sounding descriptions of experimental methods.

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What are the dynamics of a rope wrapping around a pole of given radius?

Suppose we drop a mass m from an initial angle $\theta_o$ connected to the pole of radius r with a rope of initial length $l_o$. As the system is released, the rope wraps around the pole, decreasing ...
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Do you have an idea for two easy experiments to measure the coefficients of static and sliding friction of a rope wrapped around a steel rod?

I'm researching a phenomenon dependent on the Capstan/Euler-Eytelwein-Equation. To model a simulation, I need the friction coefficients. I came up with the idea of hanging one mass $m_1$ on one side ...
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1answer
60 views

What is the scientific method for finding a theoretical explanation for experimental data?

Say you observe some effect that you did not anticipate in one of your experiments. You have checked the experimental setup and you're sure it's not just a systemic error but an actual measurement of ...
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1answer
19 views

spot welding technique

I am trying to make electrical contacts by the spot welding technique. For Hall effect measurements, the contact size should be as small as possible and the sample is very very thin(0.025mm). But ...
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1answer
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Experimental considerations for measuring the gravitational constant/effects, with two large (1000kg) masses orbiting each other? [closed]

So @uhoh, wanting to get some experimental data to verify Limits on non-Newtonian gravity at length scales larger than 1 meter?, proposed an experiment: Place two large (1000kg) spherical masses in ...
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51 views

How did Henry Kater measure distances down one part in $10^5$?

Wikipedia says that in 1817, Henry Kater was able to measure distances accurately enough to get at least five significant figures in a measurement of $g,$ suggesting that he could measure a distances ...
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3answers
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How to fix a bad KF flange?

Here is an interesting question for those who are familiar with vacuum science techniques. In the attached picture we have a damaged surface of a KF flange, which comes from the turbo pump outlet and ...
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2answers
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Torricelli's law doesn't seem to apply in an experiment. Why could this be? What is going on?

For physics class we've done this experiment where we would measure the speed of the water escaping from a water bottle through a hole in a side of it. We would calculate the speed through kinematics ...
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1answer
63 views

How can one experimentally measure the velocity of water flowing through a pipe?

I am planning to investigate the effect of bend curvature of a pipe on velocity of water. For this, I will need to find the velocity of water through various pipe bends. Would placing an object in the ...
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Porous nanostructure in TGA and DSC

How does the porosity in porous nanostructures, such as mesoporous silica, influence the observed response in Thermal Gravimetry Analysis (TGA) vs Differential scanning calorimetry (DSC) thermograms?
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1answer
70 views

What is the most efficient way to pour a liquid through a funnel?

Be it in cooking or an experiment, when transferring liquid from one container to another using a funnel should you: (a) pour it all straight into the funnel, filling it up and waiting for the liquid ...
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1answer
39 views

Strain gauge vs linear variable displacement transducer

For measuring deformation experiments, it seems that strain gauges and linear variable displacement transducers (LVDT) are commonly used. If the material exhibits geometric linearity, then couldn't we ...
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1answer
67 views

Measure temperature of a heater wire

I would like to measure the temperature of a heating wire (tungsten) that's wrapped around my sample. Does anyone have a better idea than using a infrared thermometer, which has relatively low ...
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2answers
65 views

Why are gradient and graphs used in labs? [closed]

This may seem like a redundant question but I was wondering why gradient calculations are preferred when calculating a value by experiment as opposed to just plugging in raw values me getting an ...
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1answer
48 views

The uncertainty of a toy car's measured average speed

Suppose I have a battery-powered toy car, and I am told to design an experiment which would allow me to determine the average speed of that toy car over, say, a meter, and to account for experimental ...
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1answer
61 views

Turning off an inductor: Experimental problems

I am trying to measure the current in dependence of time in turning on and off an inductor. If I choose an inductor with low inductivity (36 mH) it works for turning on (almost) as expected, but for ...
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1answer
60 views

How does one actually 'fire an electron'?

As a mathematician, I have practically zero experience and knowledge of experimental methods. Recently, learning about some famous experiments in the history of quantum physics, I heard about an ...
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1answer
81 views

Significant figures in a practical experimental problem [duplicate]

Here is a question that combines uncertainties in measurements and significant figures. Consider the following results to measure the value of g: $$g={9.7,9.8,9.7,10.0,10.1,10.3}$$ Then to four ...
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1answer
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Noise reduction approaches in optical spectral measurement

I am using an optical spectrometer to measure some surfaces in the visible, and since the signal is quite noisy I wondering what would be the best way to reduce the noise. In particular, are there ...
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2answers
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Methods to convert nitrogen nuclei to oxygen nuclei?

Are there any "safe" method that allows converting the nitrogen into oxygen? There's Ernest Rutherford that uses alpha particles aimed at the nitrogen to create oxygen and hydrogen. But are there ...
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1answer
232 views

How to find out the wavelength for the blue led diode?

I need your help as I am stuck and I dont know where to start. I have got four blue leds diode that come with dark blue led lights that I really want to get the same led colours for my 3 fans, but I ...
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4answers
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How are high-energy detectors able to to distinguish between $m_{e}$ and $m_{\mu}$?

I had a teacher pose this interesting question yesterday: Suppose you're running a high-energy scattering experiment at the LHC. For concreteness, let's suppose it's a 2 to 2 scattering event which ...
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0answers
129 views

How to cleave a perovskite single-crystal in vacuum?

I am trying to cleave the lead-halide perovskite in vacuum to study its intrinsic electronic properties using photoelectron spectroscopy, since it is difficult to remove surface adsorption without ...
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1answer
54 views

Phase-shifting by Acousto-Optic modulators

I am working on a project where I need to be able to introduce a phase-shift to a light pulse, without any mechanical parts involved. One of the options is to use an acousto-optic modulator: ...
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1answer
354 views

What are the “x” marks in a bubble chamber image?

Upon looking at a decent number of bubble chamber images I noticed an x shape . What particles are producing these trails?
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1answer
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Historic method to produce cophasal illumination before lasers?

In a bunch of old papers, written before lasers, the authors often refer to illumination with the same characteristics as a laser: single spatial mode and temporally lockstep. For example in: On the ...
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How to pass a fiber optic through an aluminum laser enclosure?

This is a very technical question which I think is not typical on this site but it is for experimental physics so I'm trying it out because I can't find a better stack exchange Problem I'm trying to ...
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1answer
61 views

X-ray: Observation of absorption edge [closed]

So I am working on this experiment on X-ray and kinda stuck on this last and following section. I have done the measurements and plotted the graph as required in 1. and 2. See below, However, I ...
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1answer
42 views

X-ray: Aluminium mass absorption co-efficient vs photon energy [closed]

I am doing this experiment on X-rays and I have to do this part of measuring aluminium mass absorption coefficient vs photon's energy. I have done all the work but now stuck in the last step (step 4). ...
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0answers
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Exclusion limits on particle dark matter

I'm trying to make sense on how the upper limits of the cross section of particle dark matter (WIMPs) are computed, like in the figure below. This is taken from an article on dark matter searches. ...
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What is the $\eta$-reflection method to estimate the background by CMS?

When I used the "Fastjet Package" to reconstruct jet and calculate the jet-shape, I need to estimate the background. I saw from paper: "The η-reflection method as the CMS experiment did, i.e., ...
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1answer
70 views

How do the LIGO team arrive at the number of round trips in the laser arm etalon?

The quoted number of laser beam round trips in the arm cavity for LIGO on the MIT site is 280 times. How did they arrive such a number? Since the laser frequency is stabilized to less than 1 Hz, the ...
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0answers
52 views

Operational definition of quantum states [closed]

I came across a basic textbook problem. I am clear with the math, but I am not clear with how it is connected with experimental facts.Before stating the actual problem. Let me quote Karl Krauss from ...
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1answer
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What are Chopper Spectrometers and how are they different from Triple-Axis Spectrometers?

I've been reading about inelastic neutron scattering experiments. Recently encountered these two techniques. Can anybody please tell me why/when are these two techniques used?
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control of accommodative and vergence demand with mirror stereoscope

I am setting up a mirror stereoscope for use in psychophysical experiments. The stereoscope will be composed of two beamsplitters equidistant from two computer displays, with the participant sitting ...
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1answer
45 views

Determining Threshold Voltage and Plateau from experimental data

I’ve been trying to figure out how to interpret the following data from the Geiger muller tube There are only seven data points. Where does the plateau begin? Has the data collection begun after the ...
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1answer
245 views

Confusion in the Michelson-Morley experiment about beam-splitter vs compensator

From what I know of the original experiment, the beam-splitter was a half-silvered mirror, and one of the paths had a compensator in the form of a glass plate. My questions are: (1) Since the glass ...
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2answers
232 views

Torsional Pendulum

Hi from one of my lab classes I had to calculate the moment of inertia of an object by turning it into a torsional pendulum, and measuring its period with a known constant A, using the following ...
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2answers
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Not seeing a diffraction pattern, what could be the cause?

Basically took a piece of paper, cut out a small slit with some scissors, and held my phone's flashlight right on the slit. What could be causing the lack of diffraction? Does the fact that the light ...
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3answers
171 views

How to detect a wormhole?

Question A wormhole is a possible solution to Einstein field equations. As far as I understand, the fact that they are a possible solution does not mean they actually exist. Are we looking for ...
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85 views

Magnetic field measured in a rotating frame

Consider that we have a magnet and a magnetometer (a fluxgate magnetometer with a single coil), standing still as shown in fig 1. In fig 1, the magnetic field measured at the axis (z1) of the ...
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What do R-squared values and percentage error indicate about the method of an experiment?

In an experiment, I plotted the data on a graph, and the R-squared value was 0.9996. I then calculated the percentage error, which was 1.47%. I know a high R-squared value indicates low random error, ...
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1answer
172 views

How to measure the electrostatic field outside of a battery?

The eletric field of a battery should look roughly like that: Assuming $1,5\,\mathrm{V}$ voltage and a distance of $5\cdot 10^{-2}\,\mathrm{m}$, the mean electric field should be in the order of ...
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1answer
381 views

Laser beam alignment: best practices

I have to build a complex optical setup consisting of many mirrors, lenses, beam-splitters, multiple wavelengths lasers to be coupled, etc. I am looking for the "best practices" to efficiently (and ...
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1answer
35 views

Dalitz plot of a top quark decay?

What would a Dalitz plot of a top quark decay look like? I haven't been able to find any in the literature, which is dominated by LHCb hadron spectroscopy, at much smaller masses than the top... ...
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1answer
41 views

Can I measure light intensity using only .jpg pictures?

I have two pictures. On first one can see a lamp shining straight into my smartphone's objective and on the second picture one can see the same lamp but covered with a piece of paper. Can I use those ...
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0answers
188 views

Why do we calculate frequency of tuning fork for longitudinal and transverse arrangement in Melde's Experiment?

Does tuning fork produces both longitudinal as well as transverse waves? Why do we determine frequency of tuning fork for both longitudinal and transverse arrangements?
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1answer
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How could we detect a dark matter particle?

If dark matter only interacts via gravity, how is detection of a dark matter particle proposed? Don't current particle detectors rely on the other (non-gravitational) interactions?
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Looking for a video of experiment with two snug-fitting glass tubes

R. Penrose in his book "Cycles of Time: An Extraordinary New View of the Universe" describes the following experiment: There are the two snug-fitting glass tubes and viscous liquid between them, with ...
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How is the electron $g$-factor determined?

I found a description of the experiments at CERN where a Penning trap is used to to determine the g-factor but I could not find the value of the radius of the circle of precession, nor could I (surely ...